VMware Infrastructure Client could not establish the initial connection with server “localhost” or “IP_Address” of the Virtual Center server.
I tried to login from my computer when I got this error. Then, I remotely accessed the server and tried to login again, I got the same error. Upon checking the services, I found out that the VMware Virtual Center service is not running. I started the service back and VC is running again now.

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Thank you!
This worked for me too =)